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821000-251 — SCREW,MACHINE

✓ Government record, cited
— · BOLT SCREW
PRODUCT OVERVIEW

821000-251: SCREW,MACHINE.

The SCREW,MACHINE is a the manufacturer industrial component. Key specifications include head_style: FLAT COUNTERSUNK, thread_class: 3A A, head_diameter: 0.827 INCHES NOMINAL IN, thread_length: 0.938 INCHES NOMINAL IN, screw_material: STEEL, fastener_length: 1.250 INCHES NOMINAL IN. This part is cataloged in the U.S.

Government catalog under NSN 5305-01-320-7317, indicating validated use in U.S. government and defense logistics supply chains. Available through authorized enterprise resellers and TPM (Third Party Maintenance) channels.

Verify compatibility with your specific system configuration before ordering.

WHERE IT FITS
821000-251
NSN: 5305-01-320-7317
FSC: 5305 — Screws
CAGE: 10001 — NAVAIR AND NAVSEA MANAGED ORIGINAL DESIGN ACTIVITY DWG NOT MATERIAL/PARTS SUPPLIER (USA)
SPECIFICATIONS
head_styleFLAT COUNTERSUNK
thread_class3A A
head_diameter0.827 INCHES NOMINAL IN
thread_length0.938 INCHES NOMINAL IN
screw_materialSTEEL
fastener_length1.250 INCHES NOMINAL IN
special_featuresPLATING BY BALVANIZE PROCESS
thread_directionRIGHT-HAND
countersink_angle60.0 DEGREES NOMINAL
internal_drive_styleSLOT
nominal_thread_diameter0.500 INCHES IN
screw_surface_treatmentZINC
NSN5305-01-320-7317
COMPONENT DIAGRAM
BOLT / SCREW — THREAD VERIFICATION REQUIRED Hex HEAD LENGTH: — THREAD: — × — MATERIAL: — PN: 821000-251 · OEM ⚠ VERIFY BEFORE ORDERING Verify thread pitch before ordering — metric (M8×1.25) ≠ imperial (5/16-18). Wrong thread = wrong part. Grade/class stamped on bolt head determines tensile strength ✓ BROKER TIP Grade/class stamped on head determines tensile strength. Grade 8 > Grade 5 > Grade 2. Always confirm head marking matches specification requirement PARTSTABLE TECHNICAL DRAWING — NOT TO SCALE
KEY FEATURES
•
SCREW SURFACE TREATMENT: ZINC
•
FASTENER LENGTH: 1.250 INCHES NOMINAL IN
•
THREAD LENGTH: 0.938 INCHES NOMINAL IN
•
NOMINAL THREAD DIAMETER: 0.500 INCHES IN
•
HEAD STYLE: FLAT COUNTERSUNK
•
THREAD DIRECTION: RIGHT-HAND
•
SCREW MATERIAL: STEEL
TECHNICAL CHARACTERISTICS
SCREW SURFACE TREATMENTZINC
FASTENER LENGTH1.250 INCHES NOMINAL IN
THREAD LENGTH0.938 INCHES NOMINAL IN
NOMINAL THREAD DIAMETER0.500 INCHES IN
HEAD STYLEFLAT COUNTERSUNK
THREAD DIRECTIONRIGHT-HAND
SCREW MATERIALSTEEL
SPECIAL FEATURESPLATING BY BALVANIZE PROCESS
INTERNAL DRIVE STYLESLOT
COUNTERSINK ANGLE60.0 DEGREES NOMINAL
OTHER ITEMS IN FSC 5305 — Screws
Items in the same Federal Supply class. No interchangeability or substitution relationship is implied.
5305-00-001-5016 5305-00-001-9160 5305-00-001-9629 5305-00-001-9742 5305-00-001-9768 5305-00-003-4306 5305-00-003-6694 5305-00-003-6753
SUBSTITUTES & CROSS-REFERENCES 2
8Z100-251Reference document
Same NSN cross-reference
Reference document — Secondary reference
8Z1000-251Reference document
Same NSN cross-reference
Reference document — Advisory reference — outside the item-of-supply concept
LIFECYCLE
NSN statusActive· U.S. Government catalog
Acquisition advice: Normally procured from the manufacturer (OEM)No demilitarization required
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FREQUENTLY ASKED QUESTIONS
What is 821000-251?
821000-251 is a SCREW,MACHINE.
What parts can replace 821000-251?
There are 2 known substitutes for 821000-251: 8Z100-251, 8Z1000-251. Substitute compatibility should be verified for your specific system.
What is the NSN for 821000-251?
821000-251 is cataloged in the U.S. Government catalog under NSN 5305-01-320-7317. This indicates validated use in U.S. government and defense supply chains.
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✓ PartsTable — the parts reference. Every fact cited to its source.
PartsTable Design LLC · partstable.com
U.S. Government catalog: edition PUBLOGDVD v12.0.0 (OCT 2026), edition date 2026-10-01, retrieved 2026-10-18.
PartsTable commercial catalog: edition Unified commercial catalog snapshot through 2026-09-28, edition date not on file, retrieved 2026-09-28.